marva4!ucdavis!VM1.MCGILL.CA!AUDITORY
Subject: Re: How much precision needed?
Message-Id: <761410196@EarLab>
Date: Wed, 16 Feb 94 14:49:56 UTC
From: marva4!EarLab.UUCP!pierre@ucdavis.edu (Pierre Divenyi)
Reducing the number of channels (provided that the width of the
channels will be inversely related to their number, as it should if
we are to cover the same frequency range) will sacrifice frequency
resolution in favor of time resolution. Since tracking envelope
fluctuations is one of the primary processes needed for speech
recognition, Bob Shannon's results make perfect sense. Plomp would
be happy to hear about them.
As far as Ed Burns's tongue-in cheek remark is concerned, obviously,
the ear has the large number of channels required for processing
a whole orchestra. However, the time-frequency trade-off still plays
(no pun): for transients (percussion, attacks) the "what" will always
matter less than the "when", even in music. Similarly, to resolve
vowels in a vowel-rich language (such as Swedish, for example), one
needs longer durations, i.e., to sacrifice time resolution. It is
the number of bits that appears to be fixed, only the distribution of
the bits varies. Gabor got the Nobel Prize for working out the details
of this trade-off. (Personally, I like better Brillouin's treatise of
the problem, for reasons of readability.)
Pierre Divenyi
PS: My ARO highlights were listening to Jim Simmons's bat IC firings,
and the dinner at Brunello's (on the expensive side but, on the other
hand, I had all my breakfasts in my room, courtesy of Publix).